This function terminates an application thread's use of the Presentation Manager and releases all of its associated resources.

#define INCL_WINWINDOWMGR /* Or use INCL_WIN, INCL_PM, Also in COMMON section */
#include <os2.h>

HAB     hab;  /*  Anchor-block handle. */
BOOL    rc;   /*  Termination indicator. */

rc = WinTerminate(hab);